At present, there is extensive documentation of the sociodemographic and health aspects of teenage pregnancy and its outcome. However, no studies-to-date have investigated the influence of familial factors (genetic and nongenetic) on teenage reproduction. Also age-differentials within the teenage population have not been examined in any detail and woman of the same age have been treated as cohorts even though their gynecological age, a measure of their reproductive-maturational status, may be different. The aim of this study is two-fold. First, we wish to clarify the relationship between gynecological age and teenage pregnancy outcome and risk, and second, we wish to examine the influence of heredity factors (in this case, between mother and daughter) and nongenetic phenomenon (which British scientists call maternal constraint) on teenage pregnancy outcome. Maternal constraint may occur if a pregnant teenager (P) has a suboptimal reproductive system due to immaturity and the metabolic demands of adolescence, and this could place subtle intrauterine "constraints" on the developing reproductive system of a female fetus (F1) which the teenager is carrying. As a result, the daughter (F1) of a teenage mother may also have a suboptimal reproductive system, there may be added risks to her and her offspring, when she becomes pregnant, and this may be compounded if she is also a teenager when she conceives.